The rate at which infants up to one year of age die in a particular region or country. The rate is calculated by taking the number of infant deaths and dividing it by the number of live births in a certain time frame. The usual time period for calculation is a calendar year. The infant mortality rate in the U. S. is declining and was 0.7% in 2002 (in other words about 7 children die of every 1000 who are born alive). In 1958, the US rate was 29 per 1000 births. The rates are much higher in poorer, developing countries. Forty percent of infant deaths are in the first month of life.